WOMS
U code network Medium severity

U0014 Medium Speed CAN Communication Bus (+) High

The OBD2 code U0014 indicates a fault in the medium speed CAN communication bus, specifically that the positive signal line is experiencing a high voltage condition, which may disrupt communication between modules

Definition

The OBD2 code U0014 indicates a fault in the medium speed CAN communication bus, specifically that the positive signal line is experiencing a high voltage condition, which may disrupt communication between modules

Common causes

  • Faulty CAN bus wiring or connectors
  • Short circuit in the CAN bus
  • Faulty or damaged CAN bus module
  • Poor ground connection
  • Interference from other electrical components
  • Corroded or loose connections
  • Faulty sensors or actuators on the CAN bus
  • Software or firmware issues in the control modules

Common misdiagnoses

  • Faulty CAN bus wiring
  • Defective CAN bus module
  • Faulty engine control unit (ECU)
  • Bad ground connections
  • Malfunctioning sensors
  • Incorrectly installed aftermarket accessories
  • Battery or charging system issues
  • Software or firmware glitches in the ECU

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context about the issue and help identify if other systems are affected

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Look for damaged, frayed, or corroded wiring in the CAN bus circuit. Pay special attention to connectors and terminals

  3. 3. Loose Connections

    Ensure that all connectors are securely attached and free of corrosion

  4. 4. Test the CAN Bus Voltage

    Use a multimeter to measure the voltage on the CAN High and CAN Low wires. The typical voltage levels should be around 2.5V when idle and should fluctuate when data is being transmitted

  5. 5. If the CAN High wire is consistently reading high (above 3.5V), it may indicate a short to power or a fault in the wiring

  6. 6. Check for Short Circuits

    Inspect the wiring for any shorts to power or ground. A short circuit can cause the CAN High line to read high

  7. 7. Disconnect the battery and use a multimeter to check for continuity between the CAN High wire and power sources

  8. 8. Test the Modules

    If possible, test the individual modules connected to the CAN bus. A faulty module can cause communication issues

  9. 9. Disconnect each module one at a time and check if the code clears or if the communication returns to normal

  10. 10. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the CAN bus communication, such as alarms, stereo systems, or other electronic devices

  11. 11. Inspect the CAN Bus Termination Resistors

    Ensure that the termination resistors (typically 120 ohms) at both ends of the CAN bus are present and functioning correctly. A missing or faulty resistor can lead to communication issues

  12. 12. Scan Tool Communication

    Use a professional scan tool to monitor the CAN bus data. This can help identify if specific modules are not communicating properly

  13. 13. Update or Reprogram Modules

    In some cases, a software update or reprogramming of the affected modules may resolve communication issues

  14. 14. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or automotive technician with experience in CAN bus systems. By following these steps, you should be able to identify and resolve the issue related to the U0014 code. Always ensure safety precautions are taken when working on vehicle electrical systems